The purpose of the proposed work for the year 1977-78 is to define the mechanism of complement mediated release of histamine catabolic enzymes from human leukocytes and to study these enzymes in established tumor cell lines. The latter studies will be directed toward defining genetic control of histaminase and histamine methyltransferase. Attempts to prepare antibodies to human histaminase and use of this antisera to immunohistochemically localize the enzyme will be undertaken. At the same time studies of human T cell suppressor and helper function will continue in an effort to define the factors that regulate the human IgE antibody response. BIBLIOGRAPHIC REFERENCES: Twarog, F.J., Weinstein, S.F., Khaw, K-T., Strieder, D.J., and Colten, H.R.: Hypersensitivity to pancreatic extracts in parents of patients with cystic fibrosis. J. All. Clin. Immunol. 59:35-40, 1977. Twarog, F.J., Picone, F.J., Strunk, R.S., So, J., and Colten, H.R.: Immediate hypersensitivity to cockroach: Isolation and purification of the major antigens. J. All. Clin. Immunol. 59:154-160, 1977.